There are numerous applications that require a laser beam to have a flat, non-Gaussian transverse profile. Commercial devices exist which accomplish a “top hat” transformation of a Gaussian beam. However, these are extremely sensitive to misalignment, divergence, and other input beam parameters. The output is also subject to diffraction effects, which degrade the flat profile.
Prior art methods and systems use refractive beam shapers. However, the prior art methods and systems are very sensitive to beam alignment, size, and divergence. Additionally, the prior art approaches inherently suffer from diffraction effects which cause the profile to change significantly in less than 0.5 meters. Wavelength can influence the diffraction rate suffered by the beam over the values for visible wavelengths. Under these conditions the useable range of prior art methods and systems is limited.
Therefore, there is a need in the art for a laser beam shaper that does not rely on ordinary refractive lenses and instead uses a series of birefringent crystal elements to produce a desired intensity profile.